Preparation

• Position a rack in the center of the oven. Put a pizza stone or an upside-down baking sheet on the rack and heat the oven to 450°F. Line a pizza peel or cookie sheet with parchment paper.
• In a 12-inch nonstick skillet, cook the sausage, peppers, onion, and garlic over medium-high heat, stirring and breaking up the sausage, until the sausage browns and the onions and peppers soften, about 5 minutes. Season to taste with salt and pepper. Remove from the heat and let cool slightly.
• Divide the dough into 4 equal pieces. Lightly flour a work surface. Using your hands or a rolling pin, stretch each piece into a 6- to 7-inch round.
• Divide the ricotta among the four rounds, placing it on one half and leaving a little room around the edge. Top with the sausage and pepper mixture and the mozzarella. Fold the dough in half over the filling. Pinch and crimp the dough either with a fork or your fingers to seal tightly.
• In a small bowl, whisk the egg with 1 Tbs. water. Brush over the calzones and sprinkle with the rosemary and a little sea salt. Transfer to the parchment-lined peel. Slide the parchment and calzones onto the hot pizza stone and bake until golden on top and bottom, 10 to 14 minutes, rotating halfway through baking.